The rolling bearings with sealing device of the known type comprise, in general:                a non-rotating outer ring suitable for being inserted inside a seat of a gear-box and provided with a radially inner raceway;        a rotating inner ring, which is arranged within the outer ring so as to be engaged by a shaft of the gear-box, defines with the outer ring an annular cavity on each side of the rolling bearing and is provided with a radially outer raceway; and        a plurality of revolving or rolling bodies placed between the outer ring and the inner ring within the raceways in order to allow the relative rotation of the inner ring with respect to the outer ring about an axis of rotation of the rolling bearing.        
The known rolling bearings of the type described above and mounted inside gear-boxes must be able to operate in environments where there is a high concentration of lubricating oil, usually in suspension inside the gear-box; therefore, they further comprise, for each side of the rolling bearing, a sealing device arranged inside the associated cavity in order to prevent the entry of contaminants inside the bearing and comprising an annular shield which is snap-engaged inside a respective annular groove formed in the outer ring in a lateral position with respect to the raceway and extends radially towards the inner ring and across the entire cavity, therefore having a free end facing the inner ring.
In particular, the free end is substantially seated inside a respective axially open annular groove which is formed in the inner ring so as to form a labyrinth seal with a complex form designed to prevent the entry of any contaminants into the bearing and is formed on each side of the inner ring alongside the associated raceway.
The need to create a labyrinth seal with a complex form between the free end and the inner ring on each side of the bearing by means of the creation of an axially open annular groove for each sealing device has the consequence that the rolling bearings with sealing device of the known type described above require relatively long machining times, which are all the longer the radially deeper the axially open annular grooves must be. Moreover, these machining times will be even longer the axially deeper these axially open annular grooves lie, and the axial depth of these axially open grooves will be all the greater the greater the axial depth inside the cavity at which the annular shield must be positioned, and/or will be all the greater the greater the difference in axial thickness of the inner ring with respect to the outer ring.